For most of the half-hour program Tuesday, the computer dominated the board, leaving "Jeopardy!" all-stars Ken Jennings and Brad Rutter in the dust. Between them, the human contenders successfully answered only a handful of questions.

The final score? Watson in the lead with a whopping $35,734, Rutter in second place with $10,400 and Jennings bringing up the rear with $4,800.

Despite Watson's impressive performance, he did leave the audience with a bit of a head-scratcher.

During Final Jeopardy, the trio was presented with the clue: "Its largest airport is named for a World War II hero; its second largest, for a World War II battle."

Rutter and Jennings successfully answered "Chicago," but Watson offered the iffy "Toronto?????" The response was even more curious, considering the category was "U.S. Cities."

David Ferrucci, the manager of the Watson project at IBM Research, said that several factors likely confused the machine. For starters, not only was the category name ("U.S. Cities") not included in the actual clue, Watson has been trained to downgrade the significance of the category because answers don't always exactly fit the category.

Ferrucci also said that Watson might have been thrown off because there are some cities named Toronto in the United States and even Toronto, Canada, includes a U.S. Major League Baseball team. Still, he added, the mistake wasn't entirely discouraging because Watson had little faith in its answer, registering a 30 percent confidence level.

Ultimately, the machine's wrong answer barely left a dent in its total winnings because Watson cleverly wagered only $947.

IBM's Watson gives one look at smart machines, click HERE for a few more.

The matchup, which was taped in January, aired on national television for the first time Monday night and wraps up tonight. The winner of the challenge will take home $1 million.

For the past four years, top artificial intelligence researchers at IBM have been preparing their mega-machine, Watson to compete on "Jeopardy!" against all-time champions Jennings and Rutter.

Watson Plays at a Very High Level, Jennings Said

In an interview with ABCNews.com last week, Jennings said that when "Jeopardy!" first called him a couple of years ago to let him know that IBM was working on a game-show machine, he said he was "skeptical."

As a former computer programmer himself, he said, he knew the computer's limitations and doubted if IBM actually could pull it off.

But when he watched taped matches of Watson playing against top human contestants, he realized that beating the computer was hardly a foregone conclusion.

"Clearly, it was playing at a very high level. It sort of effortlessly handled the kinds of things I thought computers couldn't do," he said. "It could understand wordplay, it could understand things that were more conceptual than a single fact."

For example, Jennings said an IBM developer told him that when asked for the Russian word for "goodbye," Watson gave the answer "cholesterol."

Rutter: Humanity Wins Even If Man Loses

Still, Rutter said, despite its mistakes, Watson is a very powerful computer.

"I think humans will be surprised," he told ABCNews.com. "Especially because it's just "Jeopardy!" clues like you see every day on the show. To see a computer actually figuring it out, with all the little twists and turns and puns that they like to get in there, even factoring those in. To see how well Watson is doing, I think might scare some people."

But regardless of whether Rutter, Jennings or Watson wins the match, Rutter said, no one really loses.

"Ken and I are representing humanity in this thing but, at the same time, Watson was developed, built, programmed by human beings," said Rutter. "So I think humanity wins no matter what happens."

And beyond even that, Jennings said that playing the world's most sophisticated computer gave him a new appreciation for the humble human brain.

"I was impressed at the end that the human brain -- just a few dollars worth of water and salt and protein and whatever else we have in our skulls -- that that could hang in there and play at the same level as this jillion-dollar computer the size of a room," he said. "It says a lot for the human brain that with what we have we can hang with the world's most powerful computer. It's sort of a newfound respect for what our heads can do, which we take for granted sometimes."